Unless I've got a huge gap in my memory, this doesn't in any way correspond to anything known to be connected to my LAN. I should explain that this is a mixed wired/wireless LAN. There is no security on the wireless part, but as our house is way out in the country with no other regularly inhabited house within 300m, I've always taken a relaxed view of the likelihood of somebody using my wireless connection. Normally there are 2-3 Windows PCs + 2 Linux servers on the wired LAN, plus 1-2 laptops and an iPhone, plus a Netgear router/modem, plus a simple (non-smart) switch. All of these show as expected in the nmap scan.